While numerous ceasefires agreements in the past have been short-lived, analysts say that the forthcoming elections in Sudan and increased international pressure could give this initiative a better chance of survival.

But officials warned a March 15 deadline for a final peace deal was overly ambitious.

"After the agreement is signed, the rest will come through more negotiations," said Adrees Mahmoud, a Europe-based Jem representative, who was in Qatar for the signing.

El Sadig el-Faqih, a former adviser to Sudan's president, who was also in Qatar, told Al Jazeera the move was a "framework to start discussing the details" and a peace deal could only go ahead when all parties were involved.

"It is essential for all parties to be part of it and I think the mediators are working diligently to realise this fact ... it is important to include everybody," he said.

"It is a framework, it is not the final peace agreement yet."

Darfur's other main armed group, the Sudan Liberation Army (SLA), is refusing to talk to the government, demanding an end to all violence before negotiations begin.

'Significant move'

The year-old Doha negotations have seen the dozens of smaller anti-government factions coalesce into two main groups to unify their demands.

Those groups have been irked by the separate ceasefire with Jem, but Sudan's government insisted it is committed to an inclusive peace deal.

"We believe that Darfur can't be solved bilaterally. We hope we can negotiate with the other groups to reach a final and comprehensive agreement," Amin Hassan Omar, the government official leading the negotiations, said.

The US has hailed the ceasefire deal as a "significant move" towards formal negotiations.

"The agreed ceasefire between the government of Sudan and Jem is an important first step toward reducing violence in Darfur," Philip Crowley, the US state department spokesman, said in a statement.

US officials will attend the signing, as will UN and Arab representatives and Idriss Deby, the president of Chad.

Controversial guest

Omar al-Bashir, Sudan's president, arrived in Qatar on Monday to formally sign the deal with Jem.

He has been charged with seven counts of war crimes and crimes against humanity in Darfur by the International Criminal Court (ICC), but Qatar is not a member of the ICC and has no legal obligation to arrest him.

The conflict in Darfur has ebbed over the last year and the peace deal has been bolstered by improved relations between Sudan and Chad, which have often accused each other of supporting armed groups in each others' territories.

The peace agreement is being signed in the run-up to Sudan's first multiparty elections in 24 years.

Jem, whose leader Khalil Ibrahim was a Sudan government minister before he joined the Darfur uprising, is already pressing the government to postpone the elections so that it can take part in the vote, set for April.

Darfur's seven-year conflict has claimed some 300,000 lives - both from the fighting, as well as famine and disease - and left 2.7 million refugees, according to UN figures.